A free flap is used to reconstruct various parts of the body with absent soft tissues, or for functional and aesthetic purposes. Following the first successful implementation of the free flap in 1973 by Daniel and Taylor, it has been significantly developed. The free flap is mainly used in vascular anastomoses. However, vascular anastomoses using minute sutures require much time in mastering the suture technique as well as long operation time. Moreover it carries the risk for thrombosis and total flap failure. To address these limitations, a vascular anastomosis using a minute coupling ring was developed in 1962 by Komei Nakayama et al. Since Komei Nakayama et al first introduced a vascular anastomosis using an anastomotic ring for reconstructing an oesophagus, many experimental and clinical works on mechanical anastomoses have been developed.
The mechanical anastomoses have the following characteristics. First, the mechanical anastomosis is more accurate and requires less time in mastering the operation technique than a vascular anastomosis using a suture. Secondly, it takes just about 2 to 3 minutes to perform the mechanical anastomosis. Thirdly, a monitoring result after the mechanical anastomosis is not worse than the vascular anastomosis using a suture. Fourthly, even when the diameter of a donor vessel is significantly different from that of a recipient vessel, the difference thereof can be efficiently reduced. Fifthly, the mechanical anastomosis can be efficiently performed even in a limited (small) space and a deep area of a body.